Method and means for producing loss varying with energy level



Aug. 30, L Q ROBERTS METHOD AND MEANS FOR PRODUCING LOSS VARYING WITH ENERGY LEVEL Filed June 29, 1929 flzm Z'ansm/ziss ion Zine 2 v v v v v v v v NM/WW I I A A A A A A A A v v v v v v v v lo Hams/mission Zine lze lnzfflimy E E B n INVENTOR l 6: E06 el /Li;

ATTORN EY Patented Au 30, 1932 UNITED STATES P ATE'NT OFFICE LELAND C. ROBERTS, OF TOWACO, NEW JERSEY, ASSIGNOR TOAMERIGAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW'YORK METHOD AND MEANS FOR PRODUCING LOSS VARYING WITH ENERGY. LEVEL Application filed June 29,1929. .Serial No. 374,919.

This invention relates to circuits for the communicatlon of lntelllgence, and more par- 7 ticularly to methods of and means for cntrolling the loss in transmission over Wire circuits.

The object of the invention is to eliminate or reduce to a minimum the distortion occuring in transmission over wire circuits be cause of the fact that currents of low energy levelechoes, crosstalk and noise, for instances-are transmitted with less loss than currents of higher energy level, such as voice currents.

In general, I attain the above-stated object by placing in the transmission line a network in which are arranged resistances having in one or more instances a low temperature coefficient and in one or more instances a high temperature coeflicient.

The invention will be clearly understood when the following description is read with reference to the accompanying drawing. Figure l of the drawing shows diagrammatically my circuit arrangement in one desirable form; Fig. 2 shows a modified form of the circuit arrangement of Fig. 1; and Fig. 3 shows a somewhat different arrangement for accomplishing the result of Fig. 1.

With reference to details of Fig. 1, there is shown an artificial line inserted in a transmission line and inductively connected therewith through the transformers T and T This connection through the transformers causes the impedance of the artificial line to match the impedance of the transmission circuit.

The artificial line is made up of a plurality of series impedances R R R and R These impedances take the form of resistances of low temperature coefficient. In addition to these series resistances, a resistance R of high temperature coeflicient is connected across the artificial line as shown. This shunt resistance takes the form of a short, fine, tungsten filament in an evacuated bulb. Another suitable form of a resistance of high temperature coeflicient would be a hydrogeniron ballast lamp designed to consume less energy than the ordinary commercial lamp of that type. I

'The resistance It presents a low impedance to currents of low energy level and a considerably higher impedance to currents of higher energy level. Accordingly, for currents of low energy level, there is a relatively high atively low current flow through the shunt and a relatively low loss introduced by the artificial line.

In the arrangement shown in Fig. 2 of the drawing, the artificial line is connected in the transmission line through transformers T and T The series impedances are the resistance R of low temperature coefficient and the resistance R which corresponds to the resistance R of Fig. 1 and has a high temperature coeificient. A resistance R of low temperature coefiicient is connected in shunt across the artificial line. The efi'ect of this arrangement is the opposite of the effect produced by the arrangement of Fig. 1. Specifically, the currents of low energy level have a relatively low attenuation, while in the case of currents of high energy level a relatively high loss is introduced.

A result similar to the result reached with the arrangement of Fig. 1 may be brought about by bridging a resistance of high temperature c-oeflicient, which may take the form of a ballast lamp like that shown in Fig. 1 or in Fig. 2, across a winding of a repeating coil. This arrangement is shown in Fig. 3. The coil is represented diagrammatically as comprising windings W W and W Vinding l/V may be of high or low impedance relative to windings VV and IV and across this winding W there is connected the resistance R, which is a resistance of high temperature coeflicient such as that described in connection with Figs. 1 and 2.

While the invention is specifically disclosed in certain arrangements for the purpose of illustration, it is tobe understood that the true scope of the invention is determined by the appended claims.

What is claimed is:

1. In a circuit for the transmission of altermating currents of frequencies in the range of V audibility, a transmission lineandan artificial 'line inserted in said transmission line V Y and connected therewith threugh transforma I a 5 ers, said artificial line cornprising'a' plurality A Q of series resistancesof relatlvely'low temperi aturecoefficient capableiof'abserbing angapprec'iable amennt 'o'f enfe'rgy'and a shunt rev sistance of hightemperature coefiicient. f 7 1o.- 2- 111 ;?c r nitf rt e' r smission of;al-

.n ternatinp; currents 10f frequencies in the range ofaiidibility, a transmission line andan artificiaHineI-inse'rted infs'aid transmission linen-1 ,1.

, and connected therewith threi gh transfqrrn ers, said artificial. 1ine comprising a series r resistance and a ,shunt resistance, said,resist T Tances differing from eafchether'substantially. -fastoternperature cqefiicient. 1

In testimony "whereof, I havejsi'gned my 0'} name to thisspecification this 28th" day' of 21 29 1 R. ELAN Q RO R -1 

